Re: [PATCH net v3] net: ravb: Fix possible UAF bug in ravb_remove

[Zheng Hacker]

Yunsheng Lin <linyunsheng@xxxxxxxxxx> 于2023年3月13日周一 09:15写道：
>
> On 2023/3/12 2:06, Zheng Wang wrote:
> > In ravb_probe, priv->work was bound with ravb_tx_timeout_work.
> > If timeout occurs, it will start the work. And if we call
> > ravb_remove without finishing the work, there may be a
> > use-after-free bug on ndev.
> >
> > Fix it by finishing the job before cleanup in ravb_remove.
> >
> > Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> > Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
> > Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
> > ---
> > v3:
> > - fix typo in commit message
> > v2:
> > - stop dev_watchdog so that handle no more timeout work suggested by Yunsheng Lin,
> > add an empty line to make code clear suggested by Sergey Shtylyov
> > ---
> >  drivers/net/ethernet/renesas/ravb_main.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> > index 0f54849a3823..eb63ea788e19 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > @@ -2892,6 +2892,10 @@ static int ravb_remove(struct platform_device *pdev)
> >       struct ravb_private *priv = netdev_priv(ndev);
> >       const struct ravb_hw_info *info = priv->info;
> >
> > +     netif_carrier_off(ndev);
> > +     netif_tx_disable(ndev);
> > +     cancel_work_sync(&priv->work);
>
> LGTM.
> Reviewed-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
>
> As noted by Sergey, ravb_remove() and ravb_close() may
> share the same handling, but may require some refactoring
> in order to do that. So for a fix, it seems the easiest
> way to just add the handling here.

Dear Yunsheng,

I think Sergey is right for I've seen other drivers' same handling
logic. Do you think we should try to move the cancel-work-related code
from ravb_remove to ravb_close funtion?
Appreciate for your precise advice.

Best regards,
Zheng

>
> > +
> >       /* Stop PTP Clock driver */
> >       if (info->ccc_gac)
> >               ravb_ptp_stop(ndev);
> >